A common problem for pond keepers is overwintering frogs. Most aquatic frogs overwinter
inside ponds whereas toads and some frogs overwinter in dirt outside of the pond. Frogs that
overwinter in the water include bullfrogs, green frogs, and pickerel frogs. Often
tadpoles are bought, turn into frogs, but die over the pond's first winter in climates where the
pond freezes. To increase the likelihood of frogs surviving the winter, a few things can be done.
First, as with fish, the pond should not freeze over completely. With a few rare exceptions, if the
frog freezes, it dies. Also, keeping a hole open in the ice using a de-icer, aerator, or waterfall
allows gas exchange to occur. They may seem dead but frogs are breathing very slowly through
their skin while submerged over winter. They can suffer from oxygen depletion in an iced-over
pond just as can the fish.

Frogs sometimes bury themselves in dirt and muck in the bottom of a pond but not as deeply as
an
aquatic turtle. They cannot bury too deeply too long, or they will suffocate. Therefore, it is
somewhat advantageous to leave some debris on the bottom of the pond. If the pond is too
"clean," then the addition of a container of sand or soil can provide a home for the frogs. Putting
clay soil or sand in a cat litter pan and sinking it to the bottom is one possibility. That can be
quite messy. Frogs will also
dig in to plant pots. My green frogs and bullfrogs often do not bury at all but just sit on the liner
among the leaves. A few leaves can be left on the bottom so that the frogs can sleep under them.
Finally, to reduce the chances of frogs being eaten over winter, be sure to provide lots of hiding
places as with the fish.

Over winter, frogs often turn dark and mushy and look dead. Their color tends to match that of
rotting
leaves on the bottom. On warmer winter days, they may move around a bit at the bottom.
Often, they will not respond to stimulation (much). Do not disturb them unless fungus is seen
growing on the frog, or the frog is degrading which are signs that it is in fact dead. Dead frogs
are often upside down with their tongues hanging out. A predator such as a raccoon, heron, or a
large fish would have no
problem eating an overwintering frog since they are very slow. Hiding spots can include clay
pots and PVC pipe. Most plants have died back over winter and provide little protection. Their
pots of course do provide a convenient place in which to settle.

Someone asked me if frogs hibernate with their eyes open. Well, my frogs appear to hibernate
with their eyes shut so that would be normal. Frogs that die often also have their eyes shut (if
sealed by yucky stuff) but they may be open as well. A hibernating frog should still respond to
touch somewhat. If you are not sure, remove the frog. Smell it. Look for mush or fungus. If the
frog stinks, is mushy, and does not move, it is dead. If it just died, it may be hard to tell. You
can slowly warm it up to room temperature inside. If it does not "wake up" shortly after being
warmed, it is dead. Anyway, I hope you do not find any dead frogs!! There is a photo of one
lady's hibernating frogs at
http://mywebpages.comcast.net/yurgen/frogs.html. It looks like one green frog at the top
and two large bullfrogs. The photo link was posted to rec.ponds on 12/14/02.

I was asked on 11/3/03 by Ronna at what temperature my green frogs stop being active. I would
say it is the same as the fish, about 50-55 degrees F when they no longer come out of the water.
If the air temperature is 55 or above, even if the water is a few degrees cooler, they sometimes
still come out to sun on warm fall days. If there is a warm stretch even in winter, they may come
out. They are slower and look yuckier as far as consistency and color, being more brownish
black than their summer time green and vibrant colors. Above 60 degrees and the frogs come out
for sure. In the fall, the bullfrogs, green frogs, and pickerel frogs often get on top of the nets and
bounce around. I have a section on that below.

Here is an article I wrote for Organic Gardening that includes a section on overwintering
aquatic frogs indoors.

Hibernation for Toads and Terrestrial Frogs:

Terrestrial toads hibernate by burying below the frost line. Providing lots of areas with leaf litter,
logs, and moist dirt will help toads hibernate. Terrestrial frogs such as spring peepers and
wood frogs, hibernate in cracks among rocks and logs or among leaf litter. Since these locations
freeze, so do the frogs who have a natural antifreeze in their bodies. Providing piles of rocks,
logs, and leaves can help terrestrial frogs hibernate. Also, leave some dead trees and fallen logs
around.

There seems to be a common problem in ponds with aquatic frogs where they die right about the
time that the ice melts in the ponds of colder regions. In Maryland, this happens in my ponds in
late February. Frogs that die this time of year are found upside down on the bottom of the liner.
Their tongues are usually hanging out and drained of color. Sometimes the tongues are wrapped
around their heads. The skin is usually slothing off with patches of whitish foggy skin. The
frogs are drained of their normal color but this is perfectly normal for a hibernating frog (to
blend in with the muck on the bottom of the pond). Each year, I normally lose a few frogs this
way but in the spring of 2000, I fished out over a dozen such victims. In February and March
of 2001, I removed about a dozen dead frogs, and few live frogs were seen. Frogs often die over
winter if the pond freezes over completely. Toxic gases build up under the ice and fresh oxygen
cannot get in. The frogs and fish suffocate.

My pond retained openings due to a de-icer and waterfall plus my fish were fine so I know this is
not what happened to my frogs. My pond has enough leaves in the bottom, pots, etc. for the
frogs to root into to hibernate so that was not the problem either. When I asked the newsgroup
rec.ponds about this, I got a number of replies. Some people pointed out that amphibians are
facing declines in populations and deformities throughout the world. This is very true but I do
not think it has to much to do with my particular problem. Then, someone mentioned that since
1999 was a record drought year, the frogs may not have obtained enough insects to eat before
hibernation. When the water warmed up, the frogs were simply empty of food reserves. All the
frogs did appear emaciated so this makes sense to me. I did hand feed a few frogs a few times
in the summer of 1999, and they were especially hungry. There were few insects around. Let me
know if you have any other ideas.

On 3/22/00, I found two dead green frog tadpoles as well and began to find a few more in 2000.
Perhaps my green frogs (adults and tadpoles) have been targeted by some amphibian disease or
parasite. The wood frogs seemed unaffected as they laid eggs in 2000. Of course, they
overwintered outside of the pond. In March of 2001, again a dozen or so dead green frogs and
green frog tadpoles were removed from my ponds. The fish and wood frogs experienced no
losses.

Frogs in my 153 gallon pond:

I cleaned out my 153 gallon pond on 3/26/01. There were 8
dead
green frogs, 2 dead pickerel frogs, a few dead tadpoles, and 2 dead trapdoor snails. Three live
green frogs and two live female wood frogs were found as well as hundreds of ramshorn snails
and green frog tadpoles and 19 fish. The pond is deep (2 feet) but narrow (just a few feet) so I
would bet that oxygen depletion over winter was a factor. The pond has a de-icer but I kept
switching half a dozen of them in and out as the de-icers would stop working and freeze in quite
often. The next year, I planned to put an air stone in to this pond over winter so that, hopefully,
no more frogs would suffocate! On 11/10/01, when I removed the filter for the winter and added
the de-icer, I did add an air stone, powered by a Luft pump. I hope it does the job!

Note: The Tetra Luft pump is a must-have pond supply but they no longer make it! There are
very expensive larger aeration systems that are just too big for ornamental ponds. One possible
replacement for this system might be the OASE pond-air aeration pump which costs about $53 in
2002. Two places that sell it are Aqua-Mart and Drs. Foster and Smith Aquatics. I got one, and
it is not what
I thought. It sucks air off the surface and mixes it in the pump and spews it out. It does not
look like it would work in freezing temperatures but I will use mine to add oxygen to my large
pond in summer only. I used it for one year, and it died. Guess what! Now, I see that Drs. Foster and Smith Aquatics carries the Luft
pump in
their aquarium catalog! It does not contain the outdoor cover but it looks like the same one!
You could cover it with a plastic storage box or something. I bought one on 1/25/05 and found
out that it is a Coralife Luft pump and not a Tetra Luft pump so it is different but looks like it
should work the same.

Good news! On 3/29/02, I cleaned out the 153 gallon pond and found NOT ONE DEAD FROG!
So, the air stone must have worked! I did remove a dead pickerel frog from my 1800 gallon
pond that year but that is it! I found 13 live frogs in the 153 gallon pond. They were all green
frogs. The wood frogs did not come to breed that year (probably due to the drought and
fluctuating temperatures). Only 7 live fish remained in this pond so the tadpoles, frogs, and
snails mostly had it to themselves! Here is a photo of the frogs waiting
in a pot while I cleaned the pond. You can see heads from six of them.

Bad news in 2003. When I cleaned the 153 gallon pond, I found one scrawny young green frog, a
female wood frog (who had laid eggs the week before), two green frog leg bones, and one green
frog vertebrae, and that was all the signs of frogs. The pond still had hundreds of green frog
tadpoles but something happened to the green frogs so that they never made it to overwinter (if
they had, they would be dead or the bodies still in the bottom, at least partially intact). I think the
worst drought in 100 years cut so far back on the insect prey available that they must have
starved
to death. I hope it does not mean that some predator has learned how to kill them efficiently or
the tadpoles will not stand a chance when they come out as frogs. I miss them so much! Check
out my page on green frogs and my spring 2003 newsletters for more information. On 4/30/03, I
found
my last adult male green frog; all that was left was his head, feet, and spine. The rest was bitten
off obviously. Maybe the bullfrog did it or the raccoon. There are maybe two small green frogs
left, that's it except for the tadpoles.

Update 2010: The frog populations all continue to rise and fall. In 2010, there are just a few
adult green frogs, some babies, and the only bullfrog (a female) vanished in May. Luckily, the
green frogs have laid plenty of eggs. I think the ponds are getting heavy predation from the great
blue herons, hawks, and raccoons.

During the summer of 2000, a large percentage of my previous year's tadpoles died during
metamorphosis. Through a message on the newsgroup, rec.ponds, I became aware of a new
fungus (at that time) that was occurring in the US and specifically in my state of Maryland. It is
the chytrid fungus. I am not sure if that is what my frogs and tadpoles had/have. It is said to be
carried by tadpoles and only strike them when metamorphosing. It gets frogs at any time which
fits what happened to my frogs. All frogs and changing tadpoles that died had some sloughing,
white skin. By 2010, chytrid fungus is widespread and a major problem for most
amphibians.

I am adding this section due to a number of people asking about what to do with frogs over
winter if they cannot live outside. This may be the case if the outdoor ponds are too shallow, the
frog has been a pet, the person has moved, etc. There are a few options.

1. Hope the frog leaves and finds a deeper pond. Such a pond must not freeze at the bottom, be
in good condition, and preferably have an opening in the ice over winter.

2. Move the frog to a more adequate pond.

3. Bring the frog indoors and hibernate it. The advantage of this is that it more closely matches
nature and requires little work.

4. Bring the frog indoors and keep it warm, active, and fed all winter. The advantage is that you
can monitor and enjoy the frog. While mortality this way may be lower, hibernation normally
extends the lives of those animals that hibernate and better prepares them for the breeding
triggers of spring.

Be sure to identify the frog to be sure it is an aquatic hibernator. Bullfrogs, green frogs, and
pickerel frogs hibernate under water. If the frog is a tree frog, spring peeper, wood frog, leopard
frog, or other
terrestrial frog, it hibernates on land, behind bark, around trees, or under the ground. Toads also
hibernate on land.

Hibernation Indoors for Aquatic Frogs:

Keep an aquarium or indoor pond (any non-toxic container; Rubbermaid or Sterilite storage
containers work well) in a cool area such as a garage, shed, or basement where the temperature is
preferably between 35 and 45 degrees F. Fill the container half full of water. If it is cool, the
frogs will just stay in the bottom. Land areas are not needed while aquatic frogs are
overwintering but no harm would come if they were provided. Do not feed. For cover, a few
leaves suffice. Adding dirt or sand will just make a mess. Keep the area out of direct sunlight.
Put a net or lid over the container but be sure there is good ventilation. If desired, very light
aeration will help ensure there is enough oxygen for the frogs. Strong filtration or heavy water
movement will disturb the frogs. If kept between 45 degrees and 55 degrees F for a long period
of time, the frogs will be active enough to burn off calories but not warm enough to eat so they
may starve. If no cold room is available, then the frog should be kept active and warm (at or
above 60 degrees F) as in the next section.

Keeping Aquatic Frogs Indoors and Active During the Winter:

A setup for an aquatic frog indoors over winter that is to be kept active is basically either a
terrarium or an indoor pond. Be sure to include a lid or net on the top, ventilation, filtration, and
some indirect sunlight. Frogs only eat live foods such as insects, snails, spiders, or worms. The
easiest foods to buy include crickets, mealworms, and earthworms. Aquatic frogs need both water and land
areas. They will use the water more so two-thirds water to one-third land makes sense. They
will enjoy a shallow water area where they can stand in the shallow water with their heads easily
out without having to do any work. Ideally, the water would be kept in the 60 to 75 degree F
range. The warmer it is, the more the frogs eat and the more maintenance is needed including
water changes.

Hibernation Indoors for Terrestrial Frogs and Toads:

These animals hibernate on land. They can either be hibernated or kept active. To hibernate
them, put them in a secure container such as an aquarium or plastic storage container with a lid
with ventilation holes. Keep them in a cool area such as a garage, shed, or basement where the
temperature is preferably between 35 and 45 degrees F. Fill the bottom with about half a foot of
leaves, twigs, etc. For tree frogs, add some bark or pieces of wood as well. The animals will
bury into it and wait. Do not feed. To provide appropriate moisture, there are a few options.
Into the substrate can be mixed damp sphagnum moss. Wet paper towels that are partially
squeezed dry can be placed into the container and changed every few days. A small dish of water
can be put into the setup. The setup may be misted on occasion. Toads do not need much
moisture but terrestrial frogs need more. You have to balance their need to stay moist with the
desire to prevent the growth of molds and other yucky stuff that likes moisture.

Keeping Terrestrial Frogs and Toads Indoors and Active During the
Winter:

Set the animals up in a secure aquarium. Keep them at 60 to 75 degrees F. Frogs and toads only
eat live foods such as insects, snails, spiders, or worms. The easiest foods to buy include crickets, mealworms, and earthworms.
For
the smaller animals, try wingless fruitflies too. Provide a small dish of water for them to drink.
For substrate, reptile bark, sphagnum moss, leaves, etc. may work. Dirt is usually messy.